United States Patent Office.
BENJAMIN J. MILLER, OF NEW YORK, N. Y. MODE OF FORMING A SPIRAL
FLUE FOR STEAM-BOILERS.
Specification forming part of Letters Patent No. 675, dated April
To all whom it may concern:
Be it known that I, Benjamin J. Miller, of the city and State of
New York, have invented a new and useful Improvement in Flues for
Steam-Boilers; and I do hereby declare that the following is an
exact and full description.
The nature of my improvement consists in the application to
ordinary low-pressure boilers flues of a spiral form, as
hereinafter described, for the purpose of obtaining more
compactness and strength than in the common method.
To enable others skilled in the art to make and use my invention,
I will proceed to describe its construction and operation,
reference being had to the drawing herewith deposited in the
A represents the exterior or shell of a steam-boiler and furnace
of common construction, with an opening in one side, through
which may be seen the spiral flue. The flue B is composed of a
small cylinder or core a and a larger cylinder b, forming the
exterior circumference of the flue, the cylinder being
concentric. A spiral slot or opening, corresponding in each,
extends from one end of the flue to the other, and the slot or
opening thus made is preserved and the flue made complete by
closing or joining the corresponding spiral edges of both
cylinders, so that water may flow from the inside of the inner
cylinder to the outside of the outer one, and the flame or heated
air pass through the inclosed channel between the outside surface
of the inner cylinder and the inside surface of the outer one
until it reaches the chimney d. I make use of brace or socket
bolts to give stability to such parts of the flue as may from its
size or circumstances require support or strength.
What I claim as my invention, and desire to secure by Letters
The construction and application of one or more spiral flues to
steam-boilers, as above substantially
BENJAMIN J. MILLER.
Witnesses: WM. A. Cummings, Franklin W. Stillman.